Solvation Behavior of Poly(sulfobetaine)-Based Diblock Copolymer Thin Films in Mixed Water/Methanol Vapors
Solvation Behavior of Poly(sulfobetaine)-Based Diblock Copolymer Thin Films in Mixed Water/Methanol Vapors
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DOI：
10.1021/acs.macromol.1c01179
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发表时间：
2021-07-28
期刊：
影响因子：
5.5
通讯作者：
Mueller-Buschbaum，Peter
中科院分区：
文献类型：
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作者：
Kreuzer，Lucas P.;Geiger，Christina;Mueller-Buschbaum，Peter
研究了两嵌段共聚物（DBC）薄膜在22 °C纯水蒸气和水/甲醇混合蒸气中的溶胀行为。DBC由两性离子聚（磺基甜菜碱）嵌段、聚[3-（（2-（甲基丙烯酰氧基）乙基）二甲基铵基）丙烷-1-磺酸盐]（PSPE）和非离子聚（N-异丙基甲基丙烯酰胺）（PNIPMAM）嵌段组成。在水蒸气（H2O或D2 O）中的溶胀和对甲醇蒸气交换的薄膜响应（即，一部分H2O蒸汽被CD 3OH蒸汽交换，一部分D2 O蒸汽被CH 3OH蒸汽交换），随后进行同时的飞行时间中子反射计（ToF-NR）和光谱反射计（SR）测量。与D2 O相比，暴露于H2O蒸汽导致溶胀度和吸收的H2O量略高。在甲醇交换后，PSPE-b-PNIPMAM薄膜经历两次收缩，这被分配给DBC的各个聚合物嵌段的特定响应。由于其同位素的敏感性，FTIR证实了这两个独立的收缩过程中的块在分子水平上，并揭示了每个聚合物块在水蒸气中的溶胀和甲醇交换时的作用。因此，可以建立四种不同的膜状态，其具有对蒸气组成的不同厚度依赖性，从而实现四元纳米开关。
The swelling of thin diblock copolymer (DBC) films is investigatedin situat 22 °C in pure water vapor as well as in mixed water/methanol vapor. The DBC consists of a zwitterionic poly(sulfobetaine) block, poly[3–((2-(methacryloyloxy)ethyl)dimethylammonio) propane-1-sulfonate] (PSPE), and a nonionic poly(N-isopropylmethacrylamide) (PNIPMAM) block. The swelling in water vapor (either H2O or D2O) and the thin-film response to methanol vapor exchange (i.e., a part of the H2O vapor is exchanged by CD3OH vapor and a part of the D2O vapor is exchanged by CH3OH vapor) are followed with simultaneous time-of-flight neutron reflectometry (ToF-NR) and spectral reflectance (SR) measurements.In situFourier transform infrared (FTIR) spectroscopy complements these data. Exposure to H2O vapor leads to a slightly higher degree of swelling and amount of absorbed H2O compared to D2O. Upon methanol exchange, the PSPE-b-PNIPMAM thin film undergoes two contractions, which are assigned to the specific responses of the individual polymer blocks of the DBC. Due to its isotope sensitivity, FTIR confirms these two separate contraction processes of the blocks on a molecular level and reveals the role of each polymer block during swelling in water vapor and upon the methanol exchange. Thus, four distinct film regimes with different thicknesses dependencies on the vapor composition can be established, thereby enabling a quarternary nanoswitch.